code: def __init__(self):
      self.headers = SERVICE_HEADERS
      self.req_thread = Thread(target=self._ping)
      self.req_thread.daemon = True
      self.default_frequency_secs = 10
      self.hb_url = None
  
file_path: metaflow/metaflow/metadata/heartbeat.py
imports: import time
  import requests
  import json
  from threading import Thread
  from metaflow.sidecar import MessageTypes, Message
  from metaflow.metaflow_config import SERVICE_HEADERS
  from metaflow.exception import MetaflowException
label_desc: Use image node_id 1 to create a new MetadataHeartBeat object from inherited base classes: object with example: obj = MetadataHeartBeat()